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Hepatitis B Surface Antibody, Quantitative

Test code(s) 8475

Question 1. What is the clinical indication for hepatitis B surface antibody quantitation?

Hepatitis B surface antibody quantitation is used to determine hepatitis B immune status, ie, to determine if the patient has developed immunity against the hepatitis B virus. Such immunity may develop following exposure to the hepatitis B virus or its vaccine.

Patients at higher risk of exposure to the virus include:

  • Infants born to infected mothers
  • Sex partners of infected persons
  • People with more than 1 sex partner in the last 6 months
  • People with a history of sexually transmitted infection
  • Men who have sex with men
  • Injection drug users
  • Household contacts of an infected person
  • Healthcare and safety workers who have contact with blood and body fluids
  • People who have lived or traveled in an area in which hepatitis B is common
  • People who live or work in a prison

Testing is not recommended routinely following vaccination. It is advised only for people whose subsequent clinical management depends on knowledge of their immune status. These people include:

  • Chronic hemodialysis patients
  • Immunocompromised people, including those with HIV infection, hematopoietic stem-cell transplant recipients, and people receiving chemotherapy
  • Infants born to women who test positive for the hepatitis B surface antigen
  • Sex partners of people who test positive for the hepatitis B surface antigen
  • Healthcare and public safety workers who have contact with blood or body fluids

Question 2. What is the hepatitis B surface antibody?

The hepatitis B surface antibody (anti-HBs) is the antibody that is produced in response to hepatitis B surface antigen (HbsAg), a protein present on the surface of the hepatitis B virus. Anti-HBs appears after convalescence from acute infection and lasts for many years. It can also be produced in response to hepatitis B vaccination.

Other hepatitis B antibodies (eg, antibodies against the hepatitis B core and B e antigens) are not produced in response to vaccination. This is because these antigens are not in the vaccine.

Question 3. How is the quantitative hepatitis B surface antibody (anti-HBs) test performed?

An immunometric technique is used. The anti-HBs binds to HBsAg ad and ay subtypes, which are coated on the test wells. Binding of a horseradish peroxidase-labeled HBsAg conjugate to the anti-HBs completes the “sandwich” formation. Unbound materials are then washed away. In the next step, the horseradish peroxidase catalyzes oxidation of a luminogenic substrate, producing light. Light signals are detected and quantified. Intensity of the light is proportional to the amount of anti-HBs present in the patient sample. The result is standardized to an international unit system and reported as milliinternational units per milliliter (mIU/mL).

Question 4. How are hepatitis B surface antibody (anti-HBs) results interpreted?

Results are interpreted as shown in the table.

Question 5. What is the natural history of hepatitis B surface antibody (anti-HBs) during acute hepatitis B infection and convalescence?

HBsAg can be detected in the blood 4 to 10 weeks after exposure. This corresponds to onset of symptoms and viremia detectable by nucleic acid amplification methods. Most hepatitis B infections are self-limited and are associated with disappearance of HBsAg within 4 weeks of onset of symptoms. The anti-HBs then appears and increases to a plateau level that persists indefinitely.2

Question 6. Is hepatitis B surface antibody (anti-HBs) detectable in chronic hepatitis B carriers?

No. Some acute infections in healthy adults (generally <5%) do not resolve but become persistent. In these patients, antibody response is vigorous and sustained; however, anti-HBs is not detectable in these carriers, because excess circulating HBsAg binds to the antibodies.2

Question 7. Is hepatitis B surface antibody (anti-HBs) antibody always acquired after a completed vaccination protocol?

No. After three intramuscular doses of vaccine, >90% of healthy adults and >95% of those <19 years of age develop immunity (ie, anti-HBs ≥10 mIU/mL).1 However, there is an age-specific decline in development of immunity. After age 40 years, about 90% of people become immune, but by age 60 years, only 75% of people become immune.1 Larger vaccine doses (2 to 4 times the normal adult dose) or an increased number of doses are required to induce immunity in many hemodialysis patients and in other immunocompromised people.1

References

  1. Centers for Disease Control and Prevention. Hepatitis B. http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/hepb.pdf. Accessed May 30, 2013.
  2. Ganem D, Prince AM. Hepatitis B virus infection—natural history and clinical consequences. N Engl J Med. 2004;350:1118-1129.
This FAQ is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
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